Injuries of nerves and their consequences - Reflex Sympathetic ...

54 INJURIES OF NERVES.
purpose of controlling cramps or hysteroid attacks. I
have heard patients who had heen subjected to it
speak
of the sensations accompanying the return of blood into
the limb as agonizing.
The facts here related, as to the excitability of nerves
by acids and alkalies, with the probability that much
more dilute solutions would in man cause perceptible
sensations for the existence of which in the animal we
have no test, naturally leads us to speculate upon the
share in producing or increasing pain which may be due
to chemical alterations in diseased tissues.
In nerve injuries, as I have already pointed out, the
changes in surface secretion which give rise to over-acid
or acrid sweats, may be paralleled by like chemical disturbances
in the interstitial products of the nutritive
processes, and from these may directly originate new
sources of pain and of disturbed or diminished sensation.
Probably, in this way, we are to account for the stiffness
and pain which follow intense fatigue, and which most
likely are due to accumulation in the tissues of the
material products of disintegrative change.
—
Influence of heat and cold. The eft'ect of heat upon
to desiccate
nerves, when these are exposed to the air, is
them, and therefore to produce the symptoms already
mentioned as due to desiccation.
The effect of extreme cold upon the nerve centres was
studied experimentally by the author in 1806 and '67;
and the special influence of this' agent upon nerves was
examined with care by Dr. Richardson, of London, in
1867, both making use of the spray producer invented
by the latter observer.
When a nerve is rapidly frozen by ether or rhigoleue
spray, spasms are caused at first in its connected muscles,
but in all classes of nerves the conducting power diminishes,
until finally, when absolutely frozen, it no longer